The present invention relates to a data transmission device that accommodates multiple lines and transfers data.
In particular, the invention relates to a data transmission device that multiplexes multiple optical communication paths to form one virtual communication path. This data transmission device changes the configuration of the virtual communication path in accordance with the communication capacity or operating time and turns off a nonoperating optical communication path.
With the widespread use of the Internet and the broadening of the band of content used thereon, the transmission speed of relay networks has been increased.
For the Ethernet, the current fastest transmission speed is 10 Gbits/s (see IEEE STD802.3-2008 EDITION, SECTION 4, “PART 3: CARRIER SENSE MULTIPLE ACCESS WITH COLLISION DETECTION (CSMA/CD) ACCESS METHOD AND PHYSICAL LAYER SPECIFICATIONS”, CLAUSES 44-55), and 40 Gbits/s and 100 Gbits/s-support standards are soon to make their debut (see IEEE P802.3BA TASK FORCE MEETING, MAY 2008, MUNICH, GERMANY, “BASELINE SUMMARY”). Accordingly, the transmission speed of an interface connected to a relay network of line concentrators and layer 2/layer 3 (L2/L3) gateway devices, both of which aggregate user lines (network), also must be increased in accordance with increases in the transmission speed of the relay network.
However, the bandwidth required by user lines (network) accommodated by a line concentrator or L2/L3 gateway device varies with the accommodation state and application of the user lines (network). If there are a large number of user lines (network) corresponding to broadband content such as moving images, the required bandwidth is a wide bandwidth. This may result in the exhaustion of the bandwidth of an interface connected to the relay network. In contrast, if static content is dominant, the required bandwidth may be relatively narrow. This does not result in the exhaustion of the bandwidth of an interface connected to the relay network.
As seen, the required bandwidth varies depending on the configuration of the user lines (network) accommodated by the line concentrator or L2/L3 gateway device. If the bandwidth of an interface connected to the relay network is not used to the extent that the bandwidth is exhausted, the nonoperating communication resource will be wasted.
To counter this problem, it is considered to use link aggregation (IEEE STD802.1AX-2008 EDITION, IEEE STANDARD FOR LOCAL AND METROPOLITAN AREA NETWORKS LINK AGGREGATION). In link aggregation, multiple lines can be handled as a single virtual communication path, and the bandwidth is the sum of the respective bandwidths of the connected lines. Accordingly, the communication cost can be minimized by connecting only the number of lines satisfying the required bandwidth.
In link aggregation, however, changing the number of connected lines in accordance with, for example, an increase in the required bandwidth requires line addition work. Similarly, reducing the bandwidth requires line reduction work. Further, such work involves manual setup work and a negotiation with the opposite device, thereby losing operational flexibility.
For these reasons, there has been proposed a method of performing communications using only the number of optical communication paths satisfying the required bandwidth while using wavelength-division multiplexing (see JP-A-2006-253852). This method allows a dynamic change in the combination of operating optical communication paths. As used herein, “wavelength-division multiplexing” refers to a technology where multiple optical communication paths having different wavelengths are multiplexed so that communications can be performed on a single optical fiber.